Method of making cement



Patented Nov. 17, 1925.

ANDREW GILBERT CROLL, OF WEATHERLY, PENNSYLVANIA, ASSIGNOR TO THE ATLAS PATEN OFFICE.

PORTLAND CEMENT COMPANY, A CORPORATION OF PENNSYLVANIA.

METHOD OF MAKING CEMENT.

No Drawing.

To all whom it may concern:

lie it known that I, ANDREW GILBERT CnoLL, a citizen of the United States, and a resident of VVe-atherly, county of, Carbon, and State of Pennsylvania, have invented certain new and useful Improvements in Methods of Making Cement, of which the following is a description.

My invention relates to hydraulic cement, generally known as Portland cement, and its principal object is to provide an improved method of manufacturing the same, whereby a superior product is obtained having increased tensile and compression strength.

In the manufacture of Portland cement, a calcareous substance and an argillaceous substance are mixed in properproportions and ground to a suitable fineness either in a dry state or in a wet state, and then fed into a rotary kiln, wherein the mixture iscalcined or burned by being subjected to a temperature of about 1500 C. or 2800 F. Upon completion of the burning of the material or miature, the output, which is generally known as the clinker, is removed from the kiln. I

The cement clinker is in the form of hard, granular lumps which, when it leaves the kiln, is at a white heat, since the tempera-- ture of the interior of the kiln itself is approximately 2800 F. In order that the cement clinker may be a merchantable product, it is then necessary to grind the clinker, which is done by suitable mechanical apparatus. To prevent injury to the grinding apparatus and to facilitate the handling of the hot clinker, and to facilitate the season'- ing of the cement, that is to say, to improve the quality of the cement as regards its test for soundness when subjected to the steam test, it is more or less common practice at present to apply a small stream of water to the clinker at some point between its exit from the kilns and its entrance into the grinding mills. The purpose of this is three-fold. (1) to reduce the temperature of the clinker so that it may be conveniently handled; 2) to improve its quality as regards soundness, so that the finished product will not unduly e rpand, and (3) to prevent injury to the grinding apparatus.

I am also aware of United States patents to H. Passow relating to the production of Application filed March a, 1924. Serial at. 696,687.

sow process being solely the simultaneous production of active and inert substances from furnace-slag, which process is carried out under entirely different conditions from those under which Portland cement is produced.-

I have found that a superior merchantable cement product giving to concretehigher compression and tensile strengths than heretofore obtainable, can be roduced by manufacturing cement by my lmproved' method. According to my invention, the hot cement clinker is'removed from the kiln and immediately cooled. By this I mean ably above 1500 or 1600 F., the clinker is suddenly chilled by. the application of a large quantity of cold fluid, as by quenching the clinker in a bath of cold Water, so as to greatly reduce its temperature as rapidlyas that while at a high temperature, prefer- Y possible. Sudden chilling of the highly heated clinker by the application of a large quantity of cold fluid differs radically from the application of smaller quantities of water to the partly cooled clinker. previously mentioned, and is done for a different and definite purpose. This rapid quenching or sudden chilling of the highly heated clinker is done primarily for the purpose of increasing the strength of the concrete in which my cement is used, the exact nature of the changes brought about by such ra id cooling not being understood by me at t is time. I preferably quench thehot clinker with water by applying large quantities of water to it or by immersing it in a bath of water,

although I do not limit m self to any particular manner of rapi l cooling the clinker. After the heated c inker has been rapidly cooled and dried, it is then ground into fine particles by suitable apparatus 1n the usual manner.

I have found when utilizing cement made 1 by my process, in mortars having a mixture of three parts standard Ottawa. sand and tone part of my improved cement, the tensile strength of such 'product is increased 10% or more after a seven day set, and that the compressionstrength of the same product after a' seven day set is increased or more, and after longer setting these strengths are-correspondingly increased as compared with mortars in which cement is used in the same proportions and with the same Ottawa sand as previously mentioned, .but in which no sudden 0001111 or rapid chilling of the highly heated clinker was employed. I

' I have also found that in practicing my method of making cement the higher the temperature of the clinker from which it is rapidly cooled or suddenly'quenched; the better is the product that is obtained. .In order to determinethis, I-have conducted tests, in one of which the clinker was 'sud-" denly quenched at the kiln immediately when it left the kiln; the temperature of the clinker being a white heat, or approximately 2400" F.,iand I found that the tensile strengtlrof cement mixtures was increased 10% and the compression strength.

of the same was increased 35% over the cement mixtures madefrom a cement clinker which was suddenly chilled or immersed in water at a temperature "below 1500 F.

While I have described my invention-as practiced in a specific manner,-'it should be understood that I do not limit my invention thereto, since-various modifications thereof will suggest themselves to those skilled in he cement whereby the strength ofthe result.- ing product is substantiallyincreased, which comprises burning the ingredients at am the art-without departing from the spirit of my invention, the scope of which is set forth in the annexed clalms.

What I claim and desire tovprot ect by r Letters Patent is v 1. The method of making Portland cement whereby the strength of the resulting product is substantially increased which comprises burning the ingredients at a clinkering temperature, quenching the iclin'ker substantially at said temperature in a; suitable liquid, and grinding the same.

method of making Portland landcement whereby the strength of the resulting product is substantially increased, comprising immersing the clinker at White heat in a bath of Water. 7 Signed this 29 day of February, 1924.

ANDREW G. OROLL; 

